In recent years, various sorts of information distribution systems for distributing update information for updating map data from an information distribution center to a navigation apparatus through a storage medium such as a DVD-ROM or a HDD, or a network such as a mobile phone network have been suggested.
For example, one of the suggested information distribution systems (for example, Japanese Unexamined Patent Application Publication No. 2005-331579 (paragraphs 0011 through 0028, FIGS. 1 through 4) attaches a unique ID indicating a navigation apparatus as attribute data to a storage medium on which update map data distributed from an information distribution center is stored. When the navigation apparatus uses the storage medium, the navigation apparatus determines whether its own ID coincides with the ID stored in the storage medium by determining means. When its own ID does not coincide with the stored ID, the navigation apparatus can not use update map data stored in the storage medium.